1. Field of the Invention
The present invention relates to a catalyst for use in hydrocarbon conversion processes, and more particularly to the preparation of anion modified solid acid catalysts.
2. Background of the Art
Solid acid catalysts are used in a wide variety of chemical conversion processes in the oil refining and petrochemical industries. Particularly, anion modified oxides such as WO3/ZrO2, SO4−2/ZrO2, MoO3/ZrO2, SO4−2/TiO2, and SO4−2/SnO2, are strong solid acids and have shown promising performance in hydrocarbon conversion processes such as, for example, isomerization, catalytic cracking, alkylation and transalkylation. See for example, U.S. Pat. Nos. 6,107,235 and 6,080,904.
U.S. patent application Publication No. 2003/0069131 discloses a solid acid catalyst comprising a compound of anion-modified metal oxide doped with metal ions and a method of isomerizing an alkane using the catalyst.
Catalysts prepared in accordance with prior art methods are in powder form and are not suitable for loading into most of the commercial reactors, which require catalysts formed into granules, spheres or extrudates with good mechanical strength while retaining high activity.
The solid acid catalysts mentioned above can be admixed with binders such as alumina, clay, or silica to provide shaped catalyst particles with good mechanical strength. However, the activity of the shaped bound catalysts for alkane isomerization—particularly n-heptane isomerization—is reduced significantly as compared with the unbound powder form. Accordingly, what is needed is a catalyst/binder composition which has high mechanical strength and good catalytic performance.